If you feel you are tense, try to relax your mind and body. If you start believing that you are tense, you will definitely become tense even if there are no problems.
There are many relaxation techniques but here is a simple solution:
When you wake up in the morning everyday, tell yourself quietly (in your mind) that "Today I will be relaxed and happy the whole day". Repeat it for about 5 minutes at a stretch. Do it confidently, aloud or quietly but say it as you speak normally; don’t rush it up. This is a simple use of mind power. The technique will help keeping you relaxed throughout the day unless you are bent upon being tense.
Be careful not to say that "you are not tense" or "you are not unhappy" because it will be counterproductive and will give opposite results. Your phrase should be positively worded. Do not use words like no, not, never etc. It is open to all; everyone can do it.
If you are a Reiki healer, give yourself Reiki before going to sleep at night everyday. It will help you in having sound sleep and you would wake up fresh in the morning. It helps not only in physical relaxation but also in mental relaxation making the person more composed, calm and relaxed.